The U.S. Army Corps of Engineers, New Orleans District is working to delay upriver development of salt water from the Gulf of Mexico by augmenting the sill initially constructed in July 2023.
Construction is underway to extend the present underwater sill from a depth of -55 ft to a depth of -30 ft. A 620-foot-wide navigation lane might be saved to a depth of -55 ft to make sure deep-draft delivery continues alongside the nation’s busiest inland waterway.
USACE initially constructed the underwater barrier sill in July 2023 to create a synthetic basin to delay the ingress of salt water past river mile 64 above Head of Passes. As a results of the river’s extended excessive low-flow fee, the underwater sill was overtopped Sept. 20, 2023.
“As a result of continued falling conditions, this existing sill was overtopped and the toe of the saltwater wedge has reached River Mile 69, near the community of Jesuit Bend,” stated Col. Cullen Jones, USACE New Orleans District commander. “Our modeling indicates that by augmenting the existing sill, we can support state and local preparedness and response efforts by delaying further upriver progression of the salt water by approximately 10 to 15 days.”
In addition to the sill augmentation, USACE is getting ready to move contemporary water to impacted areas. During earlier low-water occasions, comparable to 1988 and 2012, barging was used to move contemporary water to therapy services downriver of the saltwater toe.
“The Corps is securing water barges that will support impacted water treatment facilities by transporting water collected from portions of the river that do not have salinity readings,” Jones stated. “This water can then be combined with water at the municipal facility to create a mixture that is safe for treatment.”
The intrusion of salt water into the river is a naturally occurring phenomenon as a result of the underside of the riverbed between Natchez, Miss., and the Gulf of Mexico is under sea stage. Denser salt water strikes upriver alongside the underside of the river beneath the much less dense contemporary water flowing downstream. Under regular circumstances, the downstream circulate of the river prevents vital upriver development of the salt water. However, in instances of maximum low quantity water circulate, comparable to what has been occurring this yr, unimpeded salt water can journey upriver and threaten municipal ingesting water and industrial water provides. An underwater sill was constructed on 4 earlier events in 1988, 1999, 2012 and final yr in 2022.
“As new information becomes available, we will reevaluate the projected movement of the salt water and share this information with our partners and the public for their preparedness, readiness and response,” Jones stated.
